The customer service is part of the technicians job. Once we had a repair guy that didn't speak "musician". So...typically a bass player would call up and say something like, "my amp blew up". Now usually that meant that a fuse blew, possibly one of the internal fuses in the tube amps. But not getting it, his response was " oh my God!, your amp exploded!"
And a lot of things people call about really require a lot of understanding about the appliciation as well as the electronics.

For the assembly job, good soldering skills and the ability to follow instructions are the keys. If someone has the good experience and wanted to work part time that would be a possibility too. So someone gigging could work here.